I confirm this behaviour.
In my case it happens on a fresh NB7.3 install when choosing the Java tab in the options dialog. After the exception is thrown it is not possible to open the whole options dialog anymore.
Environment:
- Ubuntu 12.10
- Oracle JDK 7u15
- JGoodies Looks 2.5.3 (with jgoodies-common 1.6)
In my environment I find the GTK L&F confusing (the biggest problem is that menus have no borders and do not clearly stand out from the window when opened) while Metal is ugly. The JGoodies Looks L&F was a good compromise but this bug seriously mine the whole IDE functionality.